Method for combining logic-based circuit units and memory-based circuit units and circuit arrangement.
The present invention relates to a method for providing supply voltage potentials and ground potentials in circuit arrangements and systems with a high data transfer rate, and relates, in particular, to a method for combining logic-based circuit units and memory-based circuit units in a circuit arrangement or in a circuit system, in which different supply voltage swings are provided.
A performance of circuit arrangements and systems rises with an increasing integration density, in particular whole systems being arranged on a single chip. These circuit systems, known under the designation SoC (system on chip), have the advantage that it is possible to provide a high integration density and a functionality at a high level, although a process complexity increases in a disadvantageous manner.
In particularxe2x80x94but not exclusivelyxe2x80x94the process complexity of such systems rises by virtue of the fact that logic functions are integrated together with memory functions which are present on an SoC system. Furthermore, for cost reasons, large chip areas are fabricated in order to further increase a functionality of SoC systems. In the case of more extensive circuit systems, it is not desirablexe2x80x94or even impossiblexe2x80x94to integrate all the functionalities on a chip, in particular the functionalities are separated according to a type of functionality, e.g. into memory-based and logic-based functionalities, so that memory-based circuit units and logic-based circuit units are integrated on different chips and communicate with one another by means of interface circuit units via signals which have a defined signal voltage swing.
The fabrication process for integrated circuits on a chip can be optimized, then, for the individual types of functionality, a difference between logic-based circuit units and memory-based circuit units increasing with increasing integration and performance.
In the case of logic-based circuit units, increasingly thin gate oxides, low threshold voltages and low supply voltage potentials or supply voltage swings are used, which are provided as voltage differences between a supply voltage potential and a ground potential.
By contrast, in the case of memory-based circuit units, thick gate oxides, high threshold voltages and thus also higher supply voltage potentials or supply voltage swings are required. For cost reasons, it is not practicable in large scale integrated systems with a high transfer rate to operate logic-based circuit units and memory-based circuit units with identical or similar supply voltage potentials, ground potentials and/or supply voltage swings. In computer-aided systems, in data transfer systems and generally in complex circuit systems, different logic-based circuit units are used together with memory-based circuit units, information being exchanged between logic-based circuit units and memory-based circuit units in the form of signals with defined signal voltage swings.
FIG. 2 shows a circuit arrangement according to the prior art in which a logic-based circuit unit 101 and a memory-based circuit unit 102 are connected to one another via a signal path, information being exchanged between the memory-based circuit unit 102 and the logic-based circuit unit 101 with signals whose signal voltage swing 105 is provided between a signal voltage minimum value 110 and a signal voltage maximum value 109, the signal voltage swing 105 varying by a signal voltage swing average value 108 or an arithmetic mean.
The signal voltage swing 105 typically lies in the region of 400 mV, but smaller or larger values of the signal voltage swing 105 can also be set.
As illustrated in FIG. 2, the logic-based circuit unit 101 and the memory-based circuit unit 102 can be provided with different supply voltage potentials 103a and 103b, respectively, with respect to a ground potential 107, a supply voltage swing 111a being applied to the logic-based circuit unit 101, while a supply voltage swing 111b is applied to the memory-based circuit unit 102.
The arrow 112 illustrated on the left in FIG. 2 designates the supply voltage potential, a positive supply voltage increasing in the direction of the arrow 112 proceeding from a ground potential 107 (0 V). Consequently, a supply voltage potential 103a which is less than the ground potential 107 is applied to the logic-based circuit unit shown in FIG. 2, while a higher supply voltage potential 103b is applied to the memory-based circuit unit 102. Consequently, in the circuit arrangement shown in FIG. 2, the supply voltage swing 111a at the logic-based circuit unit 101 is likewise smaller than the supply voltage swing 111b at the memory-based circuit unit 102.
For optimization of a functionality, it is necessary, on account of the production process for integrated circuits, for the supply voltage swing 111a of the logic-based circuit unit 101 to lie below the supply voltage swing 111a of the memory-based circuit unit 102.
Consequently, it is a disadvantage of conventional circuit arrangements for combining logic-based circuit units and memory-based circuit units that a supply voltage swing cannot be reduced arbitrarily, since a predetermined signal voltage swing must be maintained in order to ensure a reliable communication between a logic-based circuit unit and a memory-based circuit unit.
With increasing integration, memory-based circuit units increasingly require supply voltage swings which can destroy logic-based circuit units or load them to an excessive extent, since the logic-based circuit units are more sensitive to high supply voltage potentials on account of their thin gate oxides.
A further disadvantage of the conventional circuit arrangement is that logic-based circuit units and memory-based circuit units are connected to an identical ground potential, thereby reducing a variability when defining a supply voltage potential for the respective circuit unit given a predetermined signal voltage swing.
A further disadvantage of conventional circuit arrangements is that a signal voltage swing average value can only be varied within narrow limits with respect to the supply voltage potentials and the ground potential.
Therefore, it is an object of the present invention to provide a method for combining logic-based circuit units and memory-based circuit units in a circuit arrangement in which different supply voltage swings are provided, a variation of the ground potential being provided in addition to a variation of the supply voltage potential.
This object is achieved according to the invention by means of the method and apparatus defined by the claims, which follow.
Further refinements of the invention emerge from the subclaims.
An essential concept of the invention consists in providing different ground potentials for logic-based circuit units and memory-based circuit units by means of the provision of different ground potential differences with respect to a reference ground potential for logic-based circuit units and memory-based circuit units.
The invention""s method for combining logic-based circuit units and memory-based circuit units in a circuit arrangement essentially has the following steps:
a) provision of at least one supply voltage potential for at least one logic-based circuit unit;
b) provision of at least one ground potential for the logic-based circuit unit;
c) provision of at least one supply voltage potential for at least one memory-based circuit unit;
d) provision of at least one ground potential for the memory-based circuit unit;
e) provision of a signal voltage swing, which is set between a signal voltage minimum value and a signal voltage maximum value, in order to enable a communication or an exchange of information between the memory-based circuit unit and the logic-based circuit unit, the signal voltage swing being applied both to the memory-based circuit unit and to the logic-based circuit unit; and
f) setting of at least one ground potential difference between the at least one ground potential of the logic-based circuit unit and the memory-based circuit unit and a reference ground potential in such a way that at least one supply voltage swing is applied to the logic-based circuit unit and the memory-based circuit unit, the signal voltage swing being provided in such a way that a supply voltage potential or a supply voltage swing of circuit units in the circuit arrangement is not exceeded.
Advantageous developments and improvements of the respective subject matter of the invention can be found in the subclaims.
In accordance with one preferred development of the present invention, the signal voltage swing in the case of logic-based circuit units is provided in the range between a signal voltage minimum value of 0.4 V and a signal voltage maximum value of 0.8 V.
In accordance with yet another preferred development of the present invention, the signal voltage swing in the case of logic-based circuit units is provided in the range between 0.4 V and 0.8 V, a signal voltage swing average value being set in such a way that the signal voltage maximum value does not exceed 1.0 V.
In accordance with yet another preferred development of the present invention, the signal voltage swing which is applied to memory-based circuit units is adapted to the signal voltage swing of the logic-based circuit units.
The invention""s circuit arrangement for combining logic-based circuit units and memory-based circuit units, in which different supply voltage swings are provided, furthermore has at least one supply voltage source, which has the following features:
a) provision of at least one supply voltage potential for at least one logic-based circuit unit;
b) provision of at least one ground potential for the logic-based circuit unit;
c) provision of at least one supply voltage potential for the at least one memory-based circuit unit, the supply voltage potential for the memory-based circuit unit being different from the supply voltage potential for the logic-based circuit unit; and
d) provision of at least one ground potential for the memory-based circuit unit, the ground potential for the memory-based circuit unit being different from the ground potential for the logic-based circuit unit.